Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 211801 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 201 PM EDT THU MAY 21 2015 .SYNOPSIS... WITH SURFACE HIGH PRESSURE SETTLING IN OVER THE REGION, DRY WEATHER IS EXPECTED FOR TODAY WITH PARTLY SUNNY SKIES FOR THIS AFTERNOON, AND TEMPERATURES RETURNING TO NEAR SEASONAL NORMALS. AN UPPER LEVEL TROUGH AND WEAK SURFACE COLD FRONT WILL BRING OUR NEXT CHANCE FOR SHOWERS ON FRIDAY, ALONG WITH A RETURN OF BELOW NORMAL TEMPERATURES. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 112 PM EDT THURSDAY...CURRENT FORECAST IN GOOD SHAPE. THE ONLY CHANGE WAS TO GO WITH MOSTLY SUNNY SKIES ACROSS THE SAINT LAWRENCE VALLEY IN NORTHERN NEW YORK AT THIS TIME. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... AS OF 416 AM EDT THURSDAY...QUIET CONDITIONS CONTINUE FOR TONIGHT AS WELL AS WE AWAIT THE APPROACH OF AN UPPER LEVEL TROUGH AND SURFACE COLD FRONT DROPPING SOUTHWARD FROM THE JAMES BAY AREA. TEMPS WILL BE SIMILAR TO THE PREVIOUS NIGHT BUT SHOULD BE A FEW DEGREES WARMER DUE TO INCREASED CLOUD COVER WHICH WILL INHIBIT ANY FROST THREAT. AS THE TROUGH AND SURFACE BOUNDARY PUSH THROUGH THE REGION FRIDAY, HAVE CONTINUED THE IDEA OF A CHANCE OF SHOWERS BUT LATEST GUIDANCE CONTINUES TO TREND ON THE DRY SIDE WITH LITTLE INSTABILITY AND AN OVERALL LACK OF MOISTURE. NOT REALLY ALL THAT EXCITED ABOUT OUR PRECIPITATION CHANCES, WHICH IF ANYTHING DOES DEVELOP WILL LIKELY AMOUNT TO ONLY A FEW HUNDRETHS OF AN INCH OF RAIN. SURFACE FRONT PUSHES EAST OF THE AREA FRIDAY NIGHT WITH HIGH PRESSURE BUILDING IN DURING THE PRE-DAWN HOURS ON SATURDAY. BRISK NORTHERLY FLOW AHEAD OF THE HIGH WILL USHER IN AN ABNORMALLY COOL AIRMASS ACROSS THE NORTH COUNTRY WITH FORECAST LOWS AREA-WIDE IN THE LOW-MID 30S WITH MID-UPPER 20S LIKELY ACROSS THE ADIRONDACKS AND NORTHEAST KINGDOM OF VERMONT. WITH THE GROWING SEASON UNDERWAY WILL LIKELY NEED SOME SORT OF FROST/FREEZE HEADLINES BUT EXACTLY WHICH IS UNCLEAR DUE TO FORECAST BOUNDARY LAYER WINDS IN THE 5-10KT RANGE. THESE WINDS WOULD LIKELY INHIBIT FROST DEVELOPMENT, BUT WITH TEMPS STILL FALLING BELOW FREEZING SENSITIVE VEGETATION WILL MOST LIKELY BE KILLED IF LEFT UNCOVERED. AS THE HIGH BUILDS OVERHEAD SATURDAY, ANOTHER DRY BUT COOL DAY IS EXPECTED WITH PLENTY OF SUNSHINE AND TEMPS IN THE UPPER 50S THE LOW 60S. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS OF 416 AM EDT THURSDAY...PRIMARY HIGHLIGHTS DURING THE EXTENDED PORTIONS OF THE FORECAST WILL BE A WARMING/MOISTENING TREND ALONG WITH INCREASING CHANCES OF SHOWERS AND A FEW STORMS, ESPECIALLY FROM MONDAY NIGHT ONWARD INTO THE MID-WEEK TIME FRAME. INITIALLY GLOBAL MODELS MAINTAIN GOOD CONSISTENCY SATURDAY NIGHT INTO SUNDAY NIGHT SHOWING MAINLY DRY WEATHER ALONG WITH TEMPERATURES RETURNING TO SEASONALLY MILD LATE SPRING NORMS. THERE APPEARS TO BE ONE LAST SURFACE TROUGH WHICH WILL ATTEMPT TO SAG INTO THE NORTHERN COUNTIES ON SUNDAY WITH PERHAPS A FEW LIGHT SHOWERS. HOWEVER, PRIMARY FORCING WILL BE EXITING OFF TO THE NORTHEAST SO THIS FEATURE WILL LIKELY WASH OUT/DISSOLVE AS IT CROSSES THE INTL BORDER SO HAVE JUST CARRIED NOMINAL 20/30 POPS NORTH ACCORDINGLY. LOWS BOTH NIGHTS IN THE 40S TO AROUND 50 WITH HIGHS ON SUNDAY BACK INTO THE UPPER 60S TO MID 70S. UNCERTAINTY THEN BEGINS TO CREEP INTO THE FORECAST FROM MONDAY ONWARD INTO TUESDAY WITH THIS MORNING`S GFS AND EUROPEAN OUTPUT REMAINING AT ODDS WITH ONE ANOTHER IN REGARD TO NORTHEASTWARD ADVANCEMENT OF A STRONG WARM FRONT INTO OUR REGION. GFS REMAINS THE FASTER OF THE TWO SOLUTIONS BRINGING WIDESPREAD SHOWERS INTO OUR NEW YORK BY MONDAY, WHEREAS THE SLOWER EUROPEAN OUTPUT WOULD SUPPRESS THE FRONT TO OUR SOUTHWEST UNTIL TUESDAY. GIVEN ROBUST THERMAL WARMING ALOFT ACROSS THE BOUNDARY, THESE DIFFERENCES MANIFEST THEMSELVES QUITE CLEARLY IN BOTH MODEL`S RESPECTIVE MOS MAX TEMP FORECASTS. GIVEN THE SEMI-PERMANENCE OF THE UPSTREAM WESTERN CONUS BLOCK IT WOULD APPEAR LINGERING NORTHWESTERLY FLOW ALOFT AND AN IDEA LEANING TOWARD THE SLOWER EUROPEAN IDEA WOULD SEEM MORE PLAUSIBLE AT THIS POINT SHOWING THE WETTER PERIODS COMING MONDAY NIGHT INTO TUESDAY. IN REGARD TO SENSIBLE WEATHER I OFFERED A GENERAL GFS/ECMWF MOS BLEND OF MAX/MIN TEMPERATURES GIVEN THE NOTED TIMING DIFFERENCES (70S & 50S), THOUGH DEPENDING ON DEGREE OF MIXING AND INSOLATION TUESDAY TEMPERATURES COULD BE CONSIDERABLY WARMER IF THE GFS DETERMINISTIC SOLUTION VERIFIES. BY WEDNESDAY INTO THURSDAY THE WARM FRONT SHOULD CLEAR NORTH AND EAST OF THE REGION AS THE NORTHEAST ENTERS A WARMER/MORE MOIST AIRMASS (PWATS TO 1.5 IN) UNDER DEEPENING SOUTHWESTERLY FLOW ALOFT. A FRONTAL BOUNDARY SAGGING INTO THE REGION ALONG WITH SUBTLE SHORTWAVE ENERGY BUNDLES SHOULD LEAD TO AFTERNOON CONVECTIVE DEVELOPMENT ON BOTH DAYS WITH AT LEAST SOME HEAVIER DOWNPOURS POSSIBLE. TEMPERATURES CONTINUE TO WARM WITH MAX TEMPERATURES LIKELY NEAR OR SLIGHTLY ABOVE 80F ON BOTH DAYS. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... THROUGH 18Z FRIDAY...VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES THROUGH 18Z FRIDAY...WITH ONLY SIGNIFICANT CHANGE WILL BE A WIND SHIFT FROM SOUTH TO NORTHWEST BEHIND A SURFACE COLD FRONT ON FRIDAY MORNING. SURFACE ANALYSIS SHOWS WEAK BOUNDARY ACROSS THE NORTHERN GREAT LAKES INTO CENTRAL CANADA ATTM...WITH A RIBBON OF MID LEVEL CLOUDS AND A WIND SHIFT. THIS FRONT WILL IMPACT OUR WESTERN TAF SITES AROUND 12Z FRIDAY AND INTO THE CHAMPLAIN VALLEY/CENTRAL VT TAF SITES BTWN 14Z-16Z FRIDAY. A BRIEF PERIOD OF MVFR CIGS ARE POSSIBLE AT SLK ASSOCIATED WITH FROPA...ALONG WITH A SPRINKLE OR LIGHT SHOWER MAINLY OVER THE MTNS. WINDS WILL INCREASE FROM THE NORTHWEST AT 10 TO 15 KNOTS WITH GUSTS TO 20 KNOTS BEHIND FRONT BY MIDDAY FRIDAY. OUTLOOK 18Z FRIDAY THROUGH TUESDAY... SFC HIGH PRESSURE BUILDS INTO THE REGION WITH VFR CONDITIONS AND BREEZY NORTHWEST WINDS ON FRIDAY AFTN. NEXT CHC FOR SCATTERED SHOWERS AND A RUMBLE OF THUNDER WILL BE EARLY NEXT WEEK WITH POTENTIAL MVFR CIGS/VIS IN THE HEAVIER SHOWERS/STORMS. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...LAHIFF NEAR TERM...WGH SHORT TERM...LAHIFF LONG TERM...JMG AVIATION...TABER

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